Polycarbonates (hereinafter referred to as "PC") are widely used in the fields of automobile, electricity and the like in view of their excellent heat resistance, impact resistance, and electric properties and sufficient dimensional stability. PC, however, suffer from high melt viscosity as well as inferior organic solvent resistance and abrasion/wear resistance, and use of PC has been limited in the fields where such properties are required. In order to obviate such drawbacks of the PC, compositions having a polyolefin resin blended in the PC have been proposed (JP-B 40-13664, JP-A 59-223741). These compositions, however, have been impractical since the low compatibility between the PC and the polyolefin resulted in delamination and poor appearance of the resulting products produced by such means as injection molding. In order to obviate such poor compatibility between the PC and the polyolefin, PC-polyolefin compositions having a polystyrene-polyolefin copolymer such as SEBS (styrene-ethylene/butylene-styrene copolymer) or SEP (styrene-ethylene/propylene copolymer) blended thereto have been proposed (JP-A 64-75543 etc.). The polystyrene-polyolefin copolymer used, however, had various properties inherent to an elastomer, and the resulting composition suffered from poor heat resistance and flexural rigidity.
JP-A 63-215750 discloses a composition comprising a PC, a polyolefin, a PC having carboxyl group in the terminal of the molecule, and a polypropylene having epoxy group. JP 63-215752 discloses a composition comprising a PC, a polyolefin, a PC having hydroxyl group in the terminal of the molecule, and a polypropylene having carboxyl group. These compositions do not undergo delamination and exhibit excellent mechanical strength and high resistance to organic solvents as well as sufficient appearance (with no delamination). The PC having carboxyl group or hydroxyl group used as a component in these compositions is produced by adding a special monomer in its polymerization process. When a manufacturer who does not have a PC polymerization plant attempts to practice such production process, a new PC polymerization plant and a large expenditure is required, and therefore, production of such composition had been quite difficult for such manufacturer. In addition, various properties remained unsatisfactory compared to those of the PC itself. Improvement in the various properties is still required.
Addition of a fluororesin such as polytetrafluoroethylene to the polycarbonate resin for the purpose of improving abrasion/wear properties is already carried out. The compositions comprising the polycarbonate and the fluororesin added thereto have good wear properties in addition to the various favorable properties of the polycarbonate resin, and such compositions have been mainly used for the components (such as gears and cams) in the fields of OA equipment, home appliance and the like which require heat resistance, impact resistance, and sliding properties. The fluororesins, however, are quite expensive and toxic gases are produced in their incineration after disposal. Accordingly, development of a new polycarbonate-based slidable material which can be used instead of such polycarbonate resin/fluororesin composition is highly awaited.
Polyolefins, and in particular, high density polyethylene, low density polyethylene, and linear low density polyethylene are inferior to the polycarbonate resin in heat resistance, flexural rigidity and flame retardancy although they are inexpensive and excellent in abrasion/wear resistance. Accordingly, it has been difficult to use a polyolefin in the fields wherein the polycarbonate/fluororesin compositions have been used. In view of such situation, attempts have been made to develop a composition having the excellent heat resistance, impact resistance, flame retardancy and the like of the polycarbonate resin and the excellent abrasion/wear resistance of the polyethylene by blending the polycarbonate and the polyethylene. Compatibility of the polycarbonate and the polyethylene, however, is extremely low, and the resins produced by merely kneading these resins suffered from delamination and surface peeling upon exposure to abrasion and wear, and hence, poor wear properties.
In view of such situation, the inventors of the present invention have found that a composition comprising a polycarbonate resin, a modified polyolefin, and an aminocarboxylic acid has excellent compatibility, wear property, mechanical properties and no delamination, and the problems as described above can be obviated by such composition, and proposed in JP-A 8-157664. This composition, however, had the problem that the flame retardancy was still insufficient for some applications. Also known is addition of a brominated polycarbonate oligomer and diantimony trioxide for the purpose of improving the flame retardancy of an aromatic polyester resin containing a polycarbonate resin (JP-A 62-172054). Such addition of diantimony trioxide to the polycarbonate resin had the problem of reduced thermal stability. JP-A 51-88551 and JP-A 61-235454 disclose frame retardant resin compositions comprising a polycarbonate resin having added diantimony tetraoxide or diantimony pentaoxide thereto. Such resins, however, were insufficient in wear property.